lib/libc/gen/ttyname.c

   1 /*
   2  * Copyright (c) 1988, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)ttyname.c        8.2 (Berkeley) 1/27/94
  30  * $FreeBSD: src/lib/libc/gen/ttyname.c,v 1.24 2007/01/09 00:27:55 imp Exp $
  31  * $DragonFly: src/lib/libc/gen/ttyname.c,v 1.14 2005/11/19 22:32:53 swildner Exp $
  32  */
  33
  34 #include "namespace.h"
  35 #include <sys/types.h>
  36 #include <sys/stat.h>
  37 #include <fcntl.h>
  38 #include <dirent.h>
  39 #include <stdlib.h>
  40 #include <termios.h>
  41 #include <unistd.h>
  42 #include <string.h>
  43 #include <paths.h>
  44 #include <errno.h>
  45 #include "reentrant.h"
  46 #include "un-namespace.h"
  47
  48 #include "libc_private.h"
  49
  50 static char ttyname_buf[sizeof(_PATH_DEV) + NAME_MAX];
  51
  52 static once_t           ttyname_init_once = ONCE_INITIALIZER;
  53 static thread_key_t     ttyname_key;
  54 static int              ttyname_keycreated = 0;
  55
  56 int
  57 ttyname_r(int fd, char *buf, size_t len)
  58 {
  59         struct stat     sb;
  60         size_t used;
  61
  62         *buf = '\0';
  63
  64         /* Must be a terminal. */
  65         if (!isatty(fd))
  66                 return (ENOTTY);
  67         /* Must be a character device. */
  68         if (_fstat(fd, &sb) || !S_ISCHR(sb.st_mode))
  69                 return (ENOTTY);
  70         /* Must have enough room */
  71         if (len <= sizeof(_PATH_DEV))
  72                 return (ERANGE);
  73
  74         strcpy(buf, _PATH_DEV);
  75         used = strlen(buf);
  76         devname_r(sb.st_rdev, S_IFCHR, buf + used, len - used);
  77         return (0);
  78 }
  79
  80 static void
  81 ttyname_keycreate(void)
  82 {
  83         ttyname_keycreated = (thr_keycreate(&ttyname_key, free) == 0);
  84 }
  85
  86 char *
  87 ttyname(int fd)
  88 {
  89         char    *buf;
  90
  91         if (thr_main() != 0)
  92                 buf = ttyname_buf;
  93         else {
  94                 if (thr_once(&ttyname_init_once, ttyname_keycreate) != 0 ||
  95                     !ttyname_keycreated)
  96                         return (NULL);
  97                 if ((buf = thr_getspecific(ttyname_key)) == NULL) {
  98                         if ((buf = malloc(sizeof ttyname_buf)) == NULL)
  99                                 return (NULL);
 100                         if (thr_setspecific(ttyname_key, buf) != 0) {
 101                                 free(buf);
 102                                 return (NULL);
 103                         }
 104                 }
 105         }
 106
 107         if (ttyname_r(fd, buf, sizeof ttyname_buf) != 0)
 108                 return (NULL);
 109         return (buf);
 110 }